WASHINGTON – The United States said on Thursday that it still does not know with certainty who was responsible for the “incidents” that last year caused “physical symptoms” among several of its diplomats in Cuba, and therefore at present it cannot blame “any country” for the situation.

State Department spokesperson Heather Nauert said at her daily press conference on Thursday that US authorities do not know precisely what happened to the diplomatic personnel and thus Washington cannot blame any individual or country, at present, for the incidents.

Nauert refused to confirm press reports saying that US diplomats in Havana were the victims of an “acoustic attack” using some sort of sound devices that caused them to lose some of their hearing.

The State Department spokesperson said that the US cannot confirm the health condition of any US citizen, whether they are inside or outside the country, saying only that the affected diplomats suffered a variety of symptoms.

The incidents came to light on Wednesday when Nauert announced that the US expelled two Cuban diplomats from the country on May 23 in response to what occurred last year to an unspecified number of US diplomatic personnel on the island.

The Cuban government said a few hours later that it had never allowed its territory to be used for “any” acts against diplomats, calling the US decision to expel the pair of Cuban diplomats “unjustified and unfounded.”

The Cuban Foreign Ministry said that when Washington informed it in February of the incidents, it launched an “exhaustive, high-priority, urgent investigation at the behest of the highest level of the Cuban government.

Nauert confirmed on Thursday that the Cuban government had provided assistance in the investigation into the incidents, which – US media reported – is being headed by the FBI, and she added that Washington and Havana are maintaining regular contacts on the matter.

Nauert had said on Wednesday that the Donald Trump administration is taking the matter “very seriously” because the Cuban government has the responsibility to protect US personnel on its territory under the Geneva Convention.

She said that the US Embassy in Havana is “completely operational” after the incidents, but she did not say if all the diplomats who returned to the US for medical treatment after the incident had been replaced.

All of the affected diplomats work for the State Department, and they began experiencing physical symptoms in late 2016, Nauert said, providing no further details about the situation but emphasizing that the investigation into the matter is continuing.

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